Revert HTTP/0.9 removal (https://codereview.chromium.org/2144803002/)

net/url_request/url_request_http_job_unittest.cc

Index: net/url_request/url_request_http_job_unittest.cc
diff --git a/net/url_request/url_request_http_job_unittest.cc b/net/url_request/url_request_http_job_unittest.cc
index c6eecb8910d21ce310bb818eaa0bf48967fdcfc0..9dd2c7dc3fbb47923c8cc3c74faff72a9d1f818e 100644
--- a/net/url_request/url_request_http_job_unittest.cc
+++ b/net/url_request/url_request_http_job_unittest.cc
@@ -176,6 +176,35 @@ TEST_F(URLRequestHttpJobWithMockSocketsTest,
             network_delegate_.total_network_bytes_received());
 }
 
+TEST_F(URLRequestHttpJobWithMockSocketsTest,
+       TestContentLengthSuccessfulHttp09Request) {
+  MockWrite writes[] = {MockWrite(kSimpleGetMockWrite)};
+  MockRead reads[] = {MockRead("Test Content"),
+                      MockRead(net::SYNCHRONOUS, net::OK)};
+
+  StaticSocketDataProvider socket_data(reads, arraysize(reads), nullptr, 0);
+  socket_factory_.AddSocketDataProvider(&socket_data);
+
+  TestDelegate delegate;
+  std::unique_ptr<URLRequest> request = context_->CreateRequest(
+      GURL("http://www.example.com"), DEFAULT_PRIORITY, &delegate);
+
+  request->Start();
+  ASSERT_TRUE(request->is_pending());
+  base::RunLoop().Run();
+
+  EXPECT_TRUE(request->status().is_success());
+  EXPECT_EQ(12, request->received_response_content_length());
+  EXPECT_EQ(CountWriteBytes(writes, arraysize(writes)),
+            request->GetTotalSentBytes());
+  EXPECT_EQ(CountReadBytes(reads, arraysize(reads)),
+            request->GetTotalReceivedBytes());
+  EXPECT_EQ(CountWriteBytes(writes, arraysize(writes)),
+            network_delegate_.total_network_bytes_sent());
+  EXPECT_EQ(CountReadBytes(reads, arraysize(reads)),
+            network_delegate_.total_network_bytes_received());
+}
+
 TEST_F(URLRequestHttpJobWithMockSocketsTest, TestContentLengthFailedRequest) {
   MockWrite writes[] = {MockWrite(kSimpleGetMockWrite)};
   MockRead reads[] = {MockRead("HTTP/1.1 200 OK\r\n"